Field of the Invention
The present invention relates to a shift register module, and in particular to a gate driving circuit integrated with a touch display panel.
Description of the Related Art
Shift registers are used widely in data transmission circuits for controlling the timing of receiving data signals at respective data lines, and they are used in gate driving circuits for generating gate driving signals at respective gate lines. In data transmission circuits, the shift registers are arranged to output a selection signal to respective data lines, and image data can be written into respective data lines in sequence. Furthermore, in gate driving circuits, the shift registers are arranged to provide a scan signal to a respective gate line to turn on the pixels of the pixel matrix in sequence, so that the image signal can be written to the respective data lines.
Recently, amorphous silicon TFT gate driver circuit (ASG) technology has been developed. In ASG technology, a gate driving circuit comprising thin film transistors (TFTs) is directly integrated into the display panel (i.e., the glass substrate of the display) during the amorphous silicon TFT process to take the place of gate driver chips. This technology also is called gate driver on panel (GOP) technology. Thus, the fabrication cost and cycle time can be reduced by ASG technology or GOP technology to reduce the use of chips in the display panel.
In current in-cell touch display panels, the touch function is integrated into the display pixels, and thus, there is no need to include a touch device other than display pixels into the display panel. For example, the touch function is integrated into liquid-crystal display (LCD) pixels or OLED pixels, and the touch function is implemented by using the electrode structures of the display pixel, so there is no need for additional touch structures. For example, when the in-cell touch display panel is a fringe field switch (FFS) LCD device, its common electrodes are usually patterned and divided into several portions to serve as touch sensing electrodes, so that the overall thickness and weight of the touch display panel can be reduced. Because the touch function is integrated into the LCD display pixels, each frame should be divided to include one or more touch sensing periods for touch detection. However, during the touch sensing periods, clock signals provided to the shift registers in the gate driving circuit are suspended or paused, and the rising edges or falling edges of gate driving signals from some shift registers are improperly extended, and the display quality of the touch display panel is degraded. Thus, there is a need for a new shift register structure capable of solving this problem.